1. Field of the Invention
This invention relates to the formation of parts from sinterable particles of material and, more specifically, to a method of rapidly removing binder from the "green" body as well as carbon formed during such binder removal in the process of formation of such parts.
2. Description of the Prior Art
The art of forming articles from particulate material is well known and examples of such systems are represented in the Strivens U.S. Pat. No. 2,939,199, Curry U.S. Pat. No. 4,011,291, Wiech, U.S. Pat. No. 4,197,116 and Wiech, U.S. Pat. No. 4,404,166, British Patent Nos. 779,242 and 1,516,079 as well as the European application of Wiech, Ser. No. 81100209.6, published July 22, 1981. While these prior art systems represent the gradual evolution in the art of manufacturing parts from particulate material with binder removal, the prior art has always suffered from the problem that the time required to remove the binder from the "green" body has been quite lengthy. In the formation of parts according to the procedures set forth in the above noted Wiech prior art, and probably in the other noted prior art, debinderizing and sintering have proceeded rapidly and without problem for small loads. However, as the load size increases in volume, for a given volume of oven or debinderizer, the required debinderizing time in particular and to some extent the sintering time increases. Also, a carbon deposit remains on and in the parts under high load when a carbon containing binder is used which deposit is not removed during the sintering step. It is postulated that the carbon deposit is a result of the pyrolytic decomposition of the binder during both the debinderizing step and the sintering step. However, as the load volume increases, the amount of water remaining in the system becomes inadequate to remove all carbon formed from the system by reaction therewith, thereby causing such carbon to be retained on and within the parts being formed. It is therefor desirable and, in fact, imperative that such carbon be removed from the system during the processing steps. It is also desirable that the debinderizing time be decreased to increase the efficiency and economics of the processing system. It is also desirable to reduce the effluent of the system by capturing the spent binder and/or its products of decomposition.